As computer technology advanced and more and more durable memory became available to console manufacturers, saving progress as a feature of a game itself became possible. Due to how computers work, that save must be a file, and memory limits might only allow one save file, a.k.a this trope. But that was the past. Now, technology makes multiple saves possible, so it's the software and therefore the game designers, not the hardware, that truly controls the number of saves that can be concurrently stored.
As one of the many possible dimensions of Save-Game Limits applicable to any game's save system, this is the "number of save slots" dimension at its harshest, since "zero" would be lacking that dimension entirely. By the way, the name is talking about save files instead of sessions because it's both shorter and it's usually one file per play session.
The other way of "saving" state is a misnomer, because password-based saving, a.k.a Password Save, is regenerating a state based on user input, instead of restoring it from a preserved location. Password Save can also overlap with this trope, since the two could often be found in the same game, using the player's resources as a form of information storage, in addition to the game storing it themselves.
As these games don't have other saves to actually select, it is possible but unlikely that a Start Screen would not exist, and instead it just does an Automatic New Game and automatically jumps into the game whenever it's turned on, instead of asking if the player would like to delete their save or some such. Although, it is unlikely since a Start Screen has other uses beyond starting the game, such as being the earliest and fastest location to access the options menu.
As a trope that isn't necessary now, if this is done in a modern game, there's likely designer intent behind it. Such as hindering Save Scumming as part of being Nintendo Hard, by making it harder to save favorable states if the wanted result has multiple points of slow failure, especially if the game only Autosaves so there's almost no player control over saving. Multiple slots allows the functional reversal of time, so having only one means that the developer assumes that there's no Unintentionally Unwinnable states that can be reached, such as the "Merciful" type of game mentioned on Unwinnable by Design. Or not, to ramp up the horror of Survival Horror with Wide-Open Sandbox, where the sandbox usually means saving anywhere is possible, for the freedom.
Another big inconvenience caused by having only one save file is the inability to dedicate specific save files to good parts of the playthrough that cannot be replayed afterwards unless the player restarts completely, like a Boss Battle, a memorable story cutscene, or a One-Time Dungeon. This can be mitigated if there's a Replay Mode of some sort present, but that feature is unfortunately rare in games of this kind.
The Roguelike genre usually does this with only Suspend Save-type saving, to keep the risky nature going, disallowing the reversal of time.
For more of a utility consideration, this might occur when giving the player a representation of the save file is not useful, like in most Puzzle Games, Rhythm Games or some other game, where each individual puzzle / stage / song usually has no impact on any other, and there's no permanent loss state, so saving and reloading later would only be a loss of progress, so it's designed so such a negative event can't happen. Then there's the common Arcade Game, Endless Game, or Game Within a Game which are only about Scoring Points, so saving the high score at the end is the only thing that's saved, and you only need one version of that.
Also, in regards to "stage-based nature", most games aren't like that anymore, so with continuity between "levels" comes possibly important changes each run, so there's a reason to allow the player to have multiple attempts at the same events, allowing player choice.
As an Anti-Frustration Feature, there might be a warning about starting a new game when a save file already exists, likely, if an Autosave might be made so early as immediately overwrite progress if a new game were started. A game's Final Death Mode could also have this, to make it even more difficult. But, just in case, some games have an option to delete the only save, perhaps for "Fresh File" Speedruns and such.
Fictional Video Games might appear to be this, especially if they're Nintendo Hard, or if it's a Massively Multiplayer Online Role-Playing Game as to keep the characters' Digital Avatars visually consistent by restricting them to only one, for instance. But this doesn't work with Minigames in general because they share the save slot with the outer game, at least in player perception.
Then there's financial considerations. Games that sell paid Loot Boxes have high overlap with this and autosaving, usually after every completed action, since allowing players to keep reloading and trying until they got what they wanted would defeat the whole purpose of the loot box mechanic.
If gameplay-impacting Character Customization is a thing, then this trope likely doesn't occur, to allow the player the space to experiment without losing previous progress.
- Drawn to Life: The second game only has one save file per game. It's possibly justified by the game itself being Adventures In Coma Land. You can't exactly have multiple save files in a universe where everything takes place in the head of supporting character Mike.
- The Legend of Zelda: Breath of the Wild: For each Nintendo Switch profile, there can only be one manual save file and five Autosaves that overwrite in oldest to newest order, for each difficulty: Normal Mode and Master Mode. However, nothing is stopping a player from making a new Switch profile on the console to have one new save file of each difficulty, so this is a play on this trope, where functionally, there's only one fully player-controlled save, but with proper manipulation, there can be 3 different timelines per profile, each with one "current" and one "previous" state saved.
- Ōkamiden has only one save file, a stark contrast to its predecessor which had 30; this is because the game was released on the Nintendo DS and, on a technical level, it already pushes the system's capacity to the limit (the first game, meanwhile, was benefited by the vast space and specs provided by the Playstation 2 and the Wii). Unfortunately, there's a good deal of collectibles that are Permanently Missable — some of which are tied into New Game Plus functionality.
- The Ratchet & Clank series has started doing this with its later PlayStation 3 games, having one save per account. This changed after Into the Nexus when fans asked for multiple saves like in the older titles, so starting with Rift Apart, multiple saves have returned. Of the Ratchet games that only have one save, there are a few variations:
- Ratchet & Clank: All 4 One: Just plain one save per account. However if you have PlayStation Plus, you can disable automatic save uploads and then use it to manually back up a specific save (or copy them to USB, of course).
- Ratchet & Clank: Full Frontal Assault: allows uploading a save file onto cloud storage (no relation to the PlayStation Plus cloud saves); while intended to be used for Cross-Saving between the PS3 and PS Vita versions of the game, it can subvert the intention of this trope by functioning as a second save slot (one save on the console, and another in the cloud).
- Ratchet & Clank: Into the Nexus is one file per local account, but it too allows save data to be uploaded to the cloud without needing PS+.
- Ratchet & Clank (2016) only has one save file per account like the game before it, but it doesn't offer cloud saves of its own accord, so PlayStation Plus is the only way to do so.
- Each game in the Super Smash Bros. series only gives the player one save file for the main game. The story modes in both Super Smash Bros. Brawl and Super Smash Bros. Ultimate meanwhile avert this, giving the player the option to hold a number of different save files at once; every other mode is still limited to one, though.
- Them's Fightin' Herds has only one save for its story mode, and choosing another chapter manually will overwrite the previous progress. Thankfully, cosmetics carry over so it's easy to play though another chapter if the player missed anything, and the only thing really lost are checkpoints.
- Bioshock Infinite allows only one save file, and combines it with auto-saves. However, each chapter already made is saved and can be overwritten by more recent plays, and players can replay these chapters. The same system is used for the Burial at Sea spin-off.
- The Far Cry franchise: Far Cry 2, Far Cry 3, Far Cry 4, Far Cry Primal, Far Cry 5, Far Cry: New Dawn and Far Cry 6, provide only a single save slot for your entire campaign. Among other things this renders you unable to replay any completed scenario.
- Singularity notably limits you to only the most recent autosave, it doesn't even have a level select feature unlike almost all other games in the genre. It does at least give you 3 seperate player profiles.
- Strife initially had only one save slot. You could save as often as you wanted, but good luck if you saved next to a boss while being low on health or ammo and with no suitable powerups in sight. Even the producers found this to be too harsh, and removed the limit in a later patch.
- Copy Kitty: The game is played by traversing through all the levels of multiple worlds, but there's only one playthrough. To restart the game would basically be un-installing, then re-installing the game, making a fresh copy.
- Crescent Pale Mist has only one save file, and progress is only saved after clearing a level. High-scores are saved on a different file however and the PC version includes a tool to wipe them without deleting the save file.
- Khimera: Destroy All Monster Girls: The Cakeboy Game Within a Game where it's all about Scoring Points, so that's the only thing that's saved.
- The LittleBigPlanet series tends to operate on a "one user, one profile" basis, which makes sense given that the saves are tied in part to the online account in respects such as Pins, Trophies, and levels uploaded.
- Mega Man: The Japan-only Complete Works re-releases of 1 through 6 for the PlayStation are aversions as they have up to 8 save slots for its Original and Navi Modes, and Mega Man 8 and its later ports on Sega Saturn and its Legacy Collection 2 version have multiple save slots on their respective platforms, however, the ports of these games featured in the Mega Man Anniversary Collection limits players to only one save file for the game.
- The Pony Platforming Project series of Fan Games of My Little Pony: Friendship Is Magic, made in Adobe Flash are short enough to only need one save file, and saving is done through reaching a Save Point. The games share a world so the mechanics are the same in each one. The games are: Minty Fresh Adventure! and Fresh Minty Adventure.
- Sonic the Hedgehog (2006): Unlike the previous games in the "Adventure" era, this game only uses one save file per Xbox/PlayStation account.
- Antichamber has only one save. You can't really let a friend try it fresh without losing your own progress. As this is a PC game, you can of course manually keep multiple copies of the save file; in fact, this is what the creator recommends doing, shrugging it off as a Do-It-Yourself Plumbing Project.note
- One Shot makes this a plot point: You, the player, only have one chance to complete the game. The original version even went as far as to lock you into a game over if you closed the game outside of designated Save Points.
- Mario Kart: Series-wide, the characters and vehicles unlocked, as well as the cups won and the Time Trial records stored, are all shared in a game's single file (64 and Double Dash!! even require additional Memory Card space to save the ghost(s) in Time Trial). Mario Kart Wii is the only game that averts the trope, thanks to having four save files.
- Pikmin 3: Only one save file is stored per Wii U account. Its two predecessors have three each. To make up for this, the game provides a rollback function allowing the player to return to a previous day, should they feel their progression is flawed (i.e. too many Pikmin lost along the way, or too little fruit juice left).
- Dragon Quest IX only has one save slot.
- Etrian Odyssey: The first four mainline games only have one save file each, but later games allow additional files to be stored via an SD card.
- The Final Fantasy Legend: A single save slot, and, unfortunately, it is possible to save in rooms that cannot be exited without a Boss Battle, with a party unable to defeat said boss.
- Paper Mario:
- Unlike the games in the series before it, Paper Mario: Color Splash only has one save file for each Wii U account.
- Paper Mario: The Origami King also only allows one save file per Nintendo Switch account.
- Pokémon: The series started as cartridge games for the Game Boy with Pokémon Red and Blue, and this trope is now presumably tradition:
- The main series games only allow one save file per slot, owing to limited cartridge space in the first generation making it the only way to nickname every possible Pokémon that the player can catch and store.
- Some of the Spin-Off games follow this trend, with examples such as Pokémon Mystery Dungeon and Pokémon Ranger
- Zig-Zagged for the Nintendo Switch games, where the device can have multiple save files by switching over to a different account. One save per account.
- Pokémon GO, as a Mobile Phone Game, also has only one save state, due to only expecting one user.
- Ring Fit Adventure: Having only one file is justified because it's Exergaming designed for only one person to use it.
- The World Ends with You: There's only one save file, and selecting the New Game option with a save file present will instead ask if the player wants to erase the existing save data.
- Undertale: There is only one save file, as a deliberately retro feature. It's a plot point, as characters remember your previous actions — even actions from a different playthrough from the current one — and some are even aware of the ability to save.
- Xenoblade Chronicles X has only one save file per Wii U account. This is due to the online features (and the achievements unlocked with them) tied to the player's profile.
- Cube Colossus: There's only Play and Load options on the start screen, and trying to Play with an existing save file gives a warning:
::WARNING::You have save file alreadyStart new game?[Yes] [No]
- Meritous: Only one save file, overwritten when the Justified Save Points are activated.
- In Animal Crossing, you are allowed one town per disc or cartridge, with up to four player characters being allowed to live in a single town; Animal Crossing: New Horizons increases this limit to eight. In most games, these characters can be deleted and swapped in for new creations whenever you desire, though Animal Crossing: New Leaf and New Horizons disallow you from deleting the first created character (who serves as the mayor/island representative) without erasing the town/island entirely.
- Tomodachi Life: A game about island management, which only allows saving one island.
- Totally Accurate Battle Simulator: The overall save saves unlocked units to use in individual battles, and how much of the campaign has been unlocked. There's no reason to reverse time.
- Invisible, Inc. has four save slots, but each one is for a separate playthrough. On each run you can only continue from your last save. You have the option of replaying a level if you fail, but procedural generation means that it won't be the same as last time.
- Metal Gear Solid 3: Snake Eater: The 3DS version only has one save file, and there's no option to store additional files through an SD card.
- Metal Gear Solid V: The Phantom Pain can only have one saved game at a time. If you want to start the game fresh, you have to erase your old game file.
- Metal Gear Survive one-ups this by limiting you to only one save slot, but making up to three extra available... at $10 a pop real-world currency. If you thought Pay To Win was bad, imagine being told you need to pay to let your brother or sister play as well.
- Resident Evil: Revelations 2 only has one save file, and it's Auto-Save only — you cannot save manually.
- Bullet Witch: Only one save file is used throughout the game, with progress being saved as players clear the game's stages. Mid-stage progress is also saved between checkpoints.
- Control: One saved path. One latest Auto-Save to reload from and a checkpoint from every plot mission completed if the player would like to turn back the clock for some reason.
- The first four Ace Attorney games only have one save slot. The Nintendo 3DS games upgrade to two saves.
- Card City Nights 1: Has only one save file because the only Character Customization is in physical appearance, and Unintentionally Unwinnable is impossible.
- Cave Story, in its original freeware version, only has one save slot. But the various upgraded ports of the game (starting with the Wiiware version) increased the save slots to three.
- In Dead Island, not only is there only 1 save file and the game saves automatically every time you do something, but the game makes it impossible to back up your save game, and destroys your save file if you're sneaky and try to do so.
- Dwarf Fortress, in both Fortress Mode and Adventure Mode, uses a save system that is under normal condition effectively the same as most roguelikes: saves are not deleted when you load them, but you can't stop the game without saving it (or finishing it, if you lose) and selecting "quit" from the main menu. Save Scumming is still possible by forcing the computer to close the program or manually copying the same file, but is considered cheating.
- FTL: Faster Than Light: One save file per installation. You can only ever have one active game at a time — if you start a new game, the current one is erased. This means you can't have separate games for different ship types saved at the same time, or have one for another person — once you start the game, you have to play it till you win, die or choose to restart and overwrite the save.
- Heaven's Vault: Single save only. Mainly saving by Auto-Save.
- I Love You, Colonel Sanders!: Saves which checkpoints have been unlocked to be able to start the game from, instead of exactly where the player ended.
- Kingdom Hearts: Melody of Memory: There's only auto-saves, so it's effectively this.
- Liberal Crime Squad allows only one save file, and auto-saves everyday to prevent Save Scumming - but it can be circumvented by the fact that savefiles still exist even when the game is being run, meaning that one could close the game and reload the savefile if the day went wrong.
- Mario Party and Mario Party 2 have each only one save file. Come Mario Party 3, and save slots were added for it and several subsequent games. Starting with Mario Party 9, the series went back to only one save file and has been like that ever since.
- Miitopia has only one save file as well.
- The three INiS DS Rhythm Games, the Osu! Tatakae! Ouendan duology and Elite Beat Agents, only allow you to keep one save file per copy of the game. Agents only allows you to save one replay per mission, while Ouendan 2 lets you save up to 20 replays of any mission without such restriction.
- PsyCard: Because it's a mobile game so space is at a premium, and only used by one person. And there's progressive unlocks without any reason to time travel backwards, since replaying the game is relatively short and easy.
- Shadow Complex only has one save file, and it is tied to the Xbox 360 profile, meaning you'll either have to start a game from the beginning from the main menu or make a new Xbox 360 profile to avoid erasing an existing file. The game's Remastered version, after an update, later averts this by adding ten save slots that can be used, however, player levels bonuses are still carried over.
- All of the Style Savvy games, Style Boutique, New Style Boutique, New Style Boutique 2: Fashion Forward, and New Style Boutique 3: Styling Star'', have only one save file.
- The Treasure Hunter Man series, a.k.a Treasure Hunter Man 1 and Treasure Hunter Man 2: Each game has only one file, so when selecting Load on the Start Screen, there's no selecting a save file, while making a new game doesn't tell the player that a save already exists.
- Understand only had one save file until a later patch added three save slots.
- Until Dawn allows you to start/restart or continue, but not load another save file. It also autosaves moment-to-moment to prevent Save Scumming. If you mess up, another teenager dies and you can either start all-over, or suck it up and move on. Sure, you can immediately quit and relaunch the game in the hopes of beating the autosave, but you can never start a new file without over-writing your progress.
- Vambrace: Cold Soul (released 2019) has three save slots, but each one is for a separate playthrough. You can quit and reload, but the game auto-saves whenever anything significant happens, so any decisions made are permanent.